In a bowl, combine the chicken cubes with Chinese cooking wine, soy sauce, baking soda, corn starch, salt, and pepper. Mix well and let it marinate for at least 30 minutes in the refrigerator.
In another bowl, whisk together chicken stock, soy sauce, rice vinegar, Chinese cooking wine, dark soy sauce, sesame oil, brown sugar, and corn starch until well combined. Set aside.
Heat 2 tablespoons of vegetable oil in a wok or large skillet over high heat.
Add the marinated chicken cubes and stir-fry until they are golden brown and cooked through. Remove the chicken from the wok and set aside.
In the same wok, add the remaining 2 tablespoons of vegetable oil.
Add minced garlic, minced ginger, dried chilies, and ground Sichuan peppercorns. Stir-fry for about 30 seconds until fragrant.
Return the cooked chicken to the wok.
Pour the prepared sauce over the chicken and stir well to coat.
Add green onion pieces and roasted peanuts. Stir-fry for another 1-2 minutes until everything is heated through and well combined.
Transfer the Kung Pao Chicken to a serving dish.
Serve hot with steamed rice or noodles.
